# 定义函数，接受歌手名和专辑名以及歌曲数的默认值
def make_album(singer_name,album_name,num_song = None):
    """
    音乐专辑
    :param singer_name: 歌手名
    :param album_name: 专辑名
    :param num_song: 歌曲数
    :return: 包含这些信息的字典
    """
    album = {'s_name': singer_name, 'a_name': album_name, }
    if num_song:
        album['n_song'] = num_song
    return album

# 调用函数
album = make_album("David Tao","黑色柳丁",12)
print(album)